MoTeC Global Forum

Hello All,
I'm hoping to gain more information about hooking up the Toyota OEM ABS speed sensors to the ADL2. I know for sure that the OEM speed sensor is a VR-Magnetic 2-wire sensors on all 4 wheels. I plan to splice them (all 4 pairs) close to the ABS module and wired them directly into the ADL2.

Question 1:
Do you see any potential problem splicing the ABS speed sensor signal close to the ABS module?

Question 2:
Does the ADL2 software has a oscilloscope screen (like the Ref Sync Capture screen in the Mx00 series) which I can test the sensor to make sure it is set up for rising or falling edge and the magnitude of the voltage when at driving speed?

Question 3:
Reading the ADL2 user manual, what does it mean by (Input Resistance : 100k ohms to groung (No Pullup)?

Thanks for the help all.

Cheers

#1) The potential problem is that the signal may be corrupted to the ABS by connecting it to the MoTeC ADL2. In theory it should be OK (see #3 below), but you will likely not have any reliable way of knowing of you've incapacitated your OEM ABS System. Now when connecting two wire sensors, you generally connect one side to the MoTeC 0V -- this will be approximately the Bat- ground that powers the ADL. You should use an ohm-meter and see if one of the ABS pins that the sensors are connected to is near the ADL 0V level.

While you say the sensors are VR, it's possible they have a current loop interface, and then you will likely not be able to just "tap into" the signals.

#2) There is no reason to worry about the edge polarity of a wheel speed data -- it is the frequency (not phase) that determines distance/speed. The monitor channels function has a low-speed oscilloscope function (click the option button) -- this is NOT the same as the Ref/Sync Capture used in ECUS, but still handy for looking at signals that move slowly (like a wheel turned by hand).

#3) It means the input is high-impedance and should have little voltage effect on the signal being measured.

Hello David,
Thanks for responding to my post.

After reading your post, I think..
#1) I will only tapped into the + signal from the speed sensor and leave the - untapped and check if ADL2 will pick up any sine wave. This way, I don't have to worry about disturbing the ABS unit? make sense or not?

#2) I agree with you that the edge might be irrelevant here but I do have the concern on the frequency of the speed sensor channel on ADL2. I believe the ABS ring has 48 tooth per revolution, do you think the ADL2 can handle it?

Let me know you thoughts.

Cheers
Andy

Regarding your wiring, you'll never know until you try connecting it and seeing what happens.

The ADL2 can handle a maximum of 3200 hz. With 48 pulses per rev, that is about 66 Rev/Sec, or about 4000 RPM.

With a 26" tall tire, 4000 RPM would equate to about 306 mph. So, you'll be ok as long as you can keep your speed below 300 mph (489 km/h).